The growth of mobile traffic volume has been exploded because of the rapid improvement of mobile devices and their applications. Heterogeneous networks (HetNets) can be an attractive solution in order to adopt the exponential growth of wireless data. Femtocell networks are accommodated within the concept of HetNets. The implementation of femtocell networks has been considered as an innovative approach that can improve the network’s capacity. However, dense implementation and installation of femtocells would introduce interference, which reduces the network’s performance. Interference occurs when two adjacent femtocells are operated with the same radio resources. In this work, a scheme, which comprises two stages, is proposed. The first step is to distribute radio resources among femtocells, where each femtocell can identify the source of the interference. A constructed table is generated in order to measure the level of interference for each femtocell. Accordingly, the level of interference for each sub-channel can be recognized by all femtocells. The second stage includes a mechanism that helps femtocell base stations adjust their transmission power autonomously to alleviate the interference. It enforces a cost function, which should be realized by each femtocell. The cost function is calculated based on the production of undesirable interference impact, which is introduced by each femtocell. Hence, the transmission power is adjusted autonomously, where undesirable interference can be monitored and alleviated. The proposed scheme is evaluated through a MATLAB simulation and compared with other approaches. The simulation results show an improvement in the network’s capacity. Furthermore, the unfavorable impact of the interference can be managed and alleviated.

This paper presents a primary investigation into developing a compact dual passband filter using novel folded-waveguide resonators with a multilayer structure. A new coupling scheme for dual-band operation is realized. Both slot and aperture couplings are used for the implementation. For the demonstration, a 4-pole dual-band filter of this type has been designed, fabricated and tested. Simulation and experimental results are presented to validate the design and to show the advantages of this type of filter.

Device-to-Device (D2D) communication is one of the most promising developments in 5G networks. D2D communication can reduce communication latency and increase spectrum efficiency and system capacity. However, implementing D2D communication in reuse mode with a traditional cellular network can result in severe interference that can significantly reduce network performance, as both networks share the same resources. It is essential to mitigate interference to improve network capacity when D2D communication coexists with traditional cellular networks. An effective power control strategy can help mitigate the potential detrimental impact of interference and maximize the potential benefits of D2D communication. In this study, a dynamic transmission power control strategy was proposed for D2D transmitters to allow them to dynamically adjust transmission power, aiming to minimize interference and maximize network capacity. The distance between and the number of D2D pairs that experience interference were the primary parameters considered for the proposed strategy, while its complexity was in polynomial time. A simulation was carried out to evaluate the proposed strategy and compare it with fixed and ranged-based approaches, and the results validated its effectiveness.

The FFR approach reduces interference between macrocells and small cells/femtocells, which are installed within macrocell’s range. Dense deployment and unplanned installation of small cells and femtocells has a detrimental impact on the performance of the system as a result of the interference. Thus, the FFR concept distributes resources to maintain interference. However, some small cells/femtocells may suffer from shortage resources. In this work, dynamic FFR mechanism has been proposed. The scheme maximizes small cell/femtocell network’s capacity. The strategy aims to boost small cell/femotcell network’s capacity and system throughput. The fundamental goal of this research is to maximize the dedicated radio resources, which are allocated to small cells/femtocells, based on a predetermined cost function. According to the cost function, which is computed for all sub-regions, the proposed dynamic FFR will allocate more radio resources to small cells/femtocells, which suffer from lack resources. The highest degree of the cost function of a certain sub-region would have the largest amount of small cells/femtocells. The sub-region with the lowest cost function would receive fewer radio resources for small cell/femtocell UEs. The throughput is utilized as a metric for the purpose of evaluating the proposed strategy. MATLAB simulation is conducted for that reason. The results show that the proposed technique outperforms the fixed FFR.

Radio frequency identification (RFID) technology has been widely used in applications such as access control, inventory management, spatial positioning, and object identification. Accurate tag estimation is one of the major challenges in RFID reader systems particularly in areas where large tag populations are to be identified such as shopping carts, warehouse inventory monitoring, and small ruminant farms. This paper proposes a new tag estimation technique employing artificial neural networks (ANNs) and signal strength to read large tag populations. The technique estimates the number of tags through the signal strength of the backscatter channel for efficient implementation of dynamic framed slotted Aloha (DFSA) protocol by analyzing the RN16 and the received signal strength indicator (RSSI). The ANN model is trained using the signal strength of various tag populations and can identify the number of tags with minimal errors. The proposed technique does not require any modification in the tags and is implemented as a minimal software script to be added to the tag estimation module of the reader. The proposed signal strength-ANN model is able to estimate the accurate number of tags thereby improving the performance of the employed DFSA model.

Femtocell networks are a promising solution to enhance the capacity of the LTE networks, especially for the indoor environments. However, unplanned deployment of the femtocells causes the co-tier interference and cross-tier interference. The interference limits the advantages of deploying the femtocell networks. The Fractional Frequency Reuse (FFR) concept is introduced to mitigate the effect of the interference on the system. In this work, Dynamic scheme is proposed to partition the spectrum efficiently. The objective of the proposed scheme is to increase the capacity of the femtocells, which enhances the performance of the system and benefits of fmetocells. The proposed scheme assign less resources for macrocell's part, which has more deployed femtocells in order to reuse as much as possible of the available resources. An experiment is conducted in order to evaluate the proposed scheme. The results indicates that the proposed scheme can increase the capacity of the system.